Temperature Controlling Method and Temperature Controller

ABSTRACT

An object of the present invention is to accurately control temperatures of microorganisms or the like. In the present invention, a temperature controller comprises a plurality of cells for storing microorganisms or the like, heaters and a cooling section. The heaters selectively heat the plurality of cells, and the cooling section wholly cools the plurality of cells. When the maximum value of temperature of a plurality of places is not lower than a first lower limit, the cooling section is driven. When a temperature of one place is not higher than a first lower limit, the heater to heat the place is driven. When the maximum value is not higher than a second lower limit, the cooling section is stopped. When a temperature of one place is not lower than a second upper limit, the heater to heat the place is not driven.

TECHNICAL FIELD

The present invention relates to a temperature controller and can, forexample, be applied to culture of microorganisms or cells (hereinafterreferred to as “microorganisms or the like”).

BACKGROUND ART

The culture speed of microorganisms or the like is sensitive to atemperature of a container (hereinafter referred to as “cell”) thathouses those (such a temperature is hereinafter referred to as “celltemperature”). It is therefore desirable to accurately control the celltemperature in culture of microorganisms or the like.

On the other hand, there may be cases where microorganisms or the likeare desired to be concurrently cultured with the cell temperatures madethe same while other conditions varied. As a technique for performingsuch culture, for example, Non-Patent Document 1 exemplifies a techniqueof using a plurality of cells with different initial values of thenumber of microorganisms or the like to concurrently culture themicroorganisms or the like.

Further, Patent Document 1 exemplifies a technique of applying a heaterand a cooling module for controlling a sample at the optimal temperaturein the biotechnology field.

Patent Document 1: Japanese Patent Laid-Open No. 9-122507

Non-Patent Document 1: “Food bacteriological examination systemDOX-60F/30F (comparison with conventional method), [online] DAIKININDUSTRIES, ltd., Mar. 22, 2005, Internet<URL:http//www.del.co.jp/products/dox/sub3.html>

However, the technique described in Patent Document 1 merely has theheater and the cooling module The technique therefore has no viewpointof accurately equating the cell temperatures when microorganisms or thelike are concurrently cultured using a plurality of cells under aplurality of different conditions except the cell temperature.

DISCLOSURE OF INVENTION

The present invention was made in view of the foregoing circumstancesand has an object to provide a technique of accurately equatingtemperatures of a plurality of containers.

A first aspect of a temperature controlling method according to thepresent invention is to control a temperature controller including: atemperature-controlled object (20) whose temperature is to becontrolled; heaters (11, 12, . . . , 1 n) for heating a plurality ofplaces of the temperature-controlled object; and a cooling section (7)for cooling the whole of the temperature-controlled object. The aspectexecutes the following steps (a) to (c): (a) a step (S10) of measuringtemperatures (T1 to Tn) of the plurality of places; (b) a step (S103,S104) of driving the cooling section when at least one of thetemperatures of the places is not lower than a first upper limit(Ts+δ1); and (c) a step (S107, S108) of driving the heater for heatingone of the places when the temperature of the one of the places is nothigher than a first lower limit (Ts−δ2).

For example, the first upper limit is a value obtained by adding a firstpositive value (81) to a target value (Ts) of a temperature of theobject (20) whose temperature is to be controlled, and the first lowerlimit is a value obtained by subtracting a second positive value (δ2)from the target value.

A second aspect of the temperature controlling method according to thepresent invention is a temperature controlling method according to thefirst aspect, and further executes the following steps (d) and (e): (d)a step (S105, S106) of not driving the cooling section when all of thetemperatures (T1 to Tn) of the places are not higher than a second lowerlimit (Ts+δ3); and (e) a step (S109, S110) of not driving the heater forheating one of the places when the temperature of the one of the placesis not lower than a second upper limit (Ts+δ4).

For example, the second lower limit is lower than the first upper limit(Ts+δ1), and is a value obtained by adding a third positive value (δ3)to the target value (Ts) of a temperature of the temperature-controlledobject (20). Further, the second upper limit is higher than the firstlower limit (Ts−δ2), and is a value obtained by adding a fourth positivevalue (δ4) to the target value.

A third aspect of the temperature controlling method according to thepresent invention is a temperature controlling method according to thesecond aspect, and further executes: (f) a step (S800) of calibrating toupdate the target value (Ts) of a temperature of the object (20) whosetemperature is to be controlled to a new target value (Tc) according toan atmospheric temperature (Ta) of the temperature controller when atleast one of the temperatures of the places is higher than the secondlower limit (Ts+δ3), all of the temperatures (T1 to Tn) of the placesare lower than the first upper limit (Ts+δ1), and any of thetemperatures of the places is higher than the first lower limit (Ts−δ2)and lower than the second upper limit (Ts+δ4). Then, the steps (b) and(c) are again executed by using the target value updated in the step(f).

It is preferable that the steps (d) and (e) be again executed by usingthe target value updated in the step (f).

A fourth aspect of the temperature controlling method according to thepresent invention is a temperature controlling method according to thefirst to third aspects, and the temperature-controlled object (20) has aplurality of containers (2) capable of housing cultures.

A first aspect of a temperature controller according to the presentinvention includes: a housing section (101), a cooling section (7), aplurality of heaters (11, 12, . . . 1 n), and a plurality of sensors(41, 42, . . . 4 n). The housing section houses a plurality ofcontainers (2) whose temperatures are to be controlled. The coolingsection concurrently cools all of the plurality containers housed in thehousing section. The plurality of heaters heat the plurality ofcontainers. The plurality of sensors measure temperatures of respectiveplaces heated by the plurality of heaters.

A second aspect of the temperature controller according to the presentinvention is a temperature controller according to the first aspect, andfurther includes a control section (6). The control section controls thedrive of the cooling section on the basis of a target value (Ts) oftemperatures of the containers. The control section also controls thedrive of the heater responsive to the sensor on the basis of eachresults of temperature measurement by the plurality of sensors.

A third aspect of the temperature controller according to the presentinvention is a temperature controller according to the second aspect,and further includes a sensor (40) and a calculating section (8). Thesensor measures an atmospheric temperature (Ta). The calculating sectionupdates the target value on the basis of the atmospheric temperature andthe target value (Ts).

A fourth aspect of the temperature controller according to the presentinvention is a temperature controller according to the second aspect,and further includes a sensor (40) and a storage section (5). The sensormeasures an atmospheric temperature (Ta). The storage section storescalibration data that provides a calibration value (Tc) on the basis ofthe atmospheric temperature and the target value (Ts). The controlsection (6) updates the target value with the calibration value on thebasis of the calibration data, the atmospheric temperature and thetarget value.

According to the first aspect of the temperature controlling methodaccording to the present invention, it is possible to enhance theaccuracy of a temperature distribution as well as the accuracy of atemperature itself. In particular, since the cooling section cools thewhole system, an atmospheric temperature is equivalently decreased inon-off control of the heater even in the case of performing thetemperature control at a temperature lower than the atmospherictemperature, which is preferred.

According to the second aspect of the temperature controlling methodaccording to the present invention, excessive cooling and excessiveheating are suppressed.

According to the third aspect of the temperature controlling methodaccording to the present invention, since the atmospheric temperature isconsidered in the temperature control, an effect on thetemperature-controlled object, exerted by the atmospheric temperature,can be made small.

According to the fourth aspect of the temperature controlling methodaccording to the present invention, since the temperature control can beperformed with accuracy in culture sensitive to temperatures, it ispossible to set a temperature condition uniformly for a plurality ofcultures.

According to the first aspect of the temperature controller of thepresent invention, it is possible to execute a temperature controlmethod according to the first to third aspects.

According to the second aspect of the temperature controller of thepresent invention, it is possible to execute the temperature controllingmethod according to the first aspect and the second aspect.

According to the third aspect and the fourth aspect of the temperaturecontroller of the present invention, it is possible to execute thetemperature controlling method according to the third aspect.

The object, characteristics, aspects and advantages of the presentinvention are made more apparent by means of the following detailedexplanations and attached drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual perspective view of a temperature controlleraccording to a first embodiment of the present invention.

FIG. 2 is a sectional view at a position AA and a position BB of thetemperature controller shown in FIG. 1.

FIG. 3 is a plan view exemplifying a positional relation between holes21 and a heater group 1.

FIG. 4 is a flowchart exemplifying a temperature controlling methodaccording to the first embodiment of the present invention.

FIG. 5 is a flowchart exemplifying a temperature controlling methodaccording to a second embodiment of the present invention.

FIG. 6 is a flowchart exemplifying a temperature controlling methodaccording to a third embodiment of the present invention.

FIG. 7 is a flowchart exemplifying a temperature controlling methodaccording to the third embodiment of the present invention.

FIG. 8 is a block diagram exemplifying a configuration of a fourthembodiment of the present invention.

FIG. 9 is a block diagram exemplifying another configuration of thefourth embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

In the following, a description is made by taking a case as an examplewhere a temperature control technique according to the present inventionis applied to culture of microorganisms or the like. However, thetemperature control technique according to the present invention isapplicable to cases other than the case of culture of microorganisms orthe like.

First Embodiment

FIG. 1 is a conceptual perspective view of a temperature controlleraccording to the present embodiment. FIGS. 2( a) and (b) are sectionalviews at a position AA and a position BB of the temperature controllershown in FIG. 1. The temperature controller includes a cell group 20, acase 101 as a housing section for housing the cell group 20, and aheater group 1 and a cooling section 7 which are both supplied forcontrolling a cell temperature. The cell group 20 is comprised of aplurality of cells 2 as containers for housing microorganisms or thelike.

The case 101 is provided with a plurality of holes 21 for housing thecell group 20. For example, the cell 2 has an opening for pouringmicroorganisms or the like and a lid for closing the opening. The cells2 are housed in the holes 21 such that the opening side is located onthe surface side of the case 101.

It is to be noted that as shown in FIG. 1, the temperature controllermay be provided with the cover 100. It is aimed at preventing foreignmaterials such as dust from getting in the holes 21.

The heater group 1 is provided in the peripheries of the cells 2. Thecooling section 7 has a cooling fan 71, a cooling fin 72, an aluminumconductive block 73, a Peltier device 74, a radiation fin 75, and aradiation fan 76.

The cooling fan 71 sends air in the vicinity of the cell group 20 to thecooling fin 72 along a channel 701. The air cooled by the cooling fin 72is sent to the vicinity of the cell group 20 along a channel 702. Bysuch circulation and cooling of the air, all of the cells 2 housed inthe case 101 are concurrently cooled. Even when the air flows in adirection opposite to the channels 701 and 702, the cell group 20 iscooled.

The heat obtained by the cooling fin 72 is provided to the aluminumconductive block 73. The Peltier device 74 shifts the heat from thealuminum conductive block 73 side to the radiation fin 75 side. The heatshifted to the radiation fin 75 is released to the outside by theradiation fan 76.

FIG. 3 is a plan view exemplifying the positional relationship betweenthe holes 21 and the heater group 1. However, the representation of thecase 101 itself is omitted for avoiding complexity of the illustration.

The heater group 1 has a plurality of heaters 11, 12, . . . 1 n. Thecells 2 are housed in the holes 21. The holes 21 are adjacent to one ormore heaters through heat blocks 3. This allows selective heating of thecell 2 by the heater group 1.

For example, the holes 21 arranged in a position C in the figure areadjacent to the heater 11 from both sides in a direction orthogonal tothe arrangement of the holes 21 via different heat blocks 3. Further,the holes 21 arranged in a position D are adjacent to the heater 11 fromone side and adjacent to the heater 12 from the other side in thedirection orthogonal to the arrangement via different heat blocks 3.

One of the heat blocks 3 adjacent to the heaters 1 k (k=1, 2, . . . n)is provided with a sensor 4 k for measuring a temperature of a placeheated by the heater 1 k.

FIG. 4 is a flowchart exemplifying a temperature controlling methodaccording to the present embodiment. An object whose temperature is tobe controlled is the cell group 20, and more specifically the whole ofthe cells 2 housed in the case 101. The temperature of the heat block 3is adopted as the cell temperature. This is because insertion of thecensor into the cell 2 in culturing microorganisms or the like insidethe cell 2 is not preferred, and the cells 2 housed in the holes 21adjacent to the heat block 3 are considered to exhibit an almost uniformcell temperature with the temperature of the heat block 3.

As thus described, a plurality of cells 2 are present each as the objectwhose temperature is to be controlled, and the heaters 11, 12, . . . , 1n selectively heat a plurality of places. On the other hand, the coolingsection 7 cools the whole of the objects whose temperatures are to becontrolled.

A target value of the cell temperature desired to be set is Ts. Thistarget value is common to all the cells 2. When an operational switch ofthe temperature controller is turned on, first, in Step S101,temperatures T1 to Tn of a plurality of places heated by the heaters 11,12, . . . , 1 n are measured. Specifically, the temperatures T1 to Tnare measured by censors 41 to 4 n.

Next, in Step S103, it is determined whether or not at least one ofthose temperatures Tk is not smaller than a prescribed upper limit(Ts+δ1). In FIG. 4, it is shown using a symbol ∃ that the temperature Tkis present which satisfies a condition represented to the right of acolon, namely a condition of being not smaller than the upper limit(Ts+δ1). Here, for example, δ1 is a positive value and 1° C. is adopted.

When it is determined that at least one cell is present which isresponsive to the temperature Tk satisfying the condition of Step S103,the process proceeds to Step S104, and the cooling section 7 is driven.Then returning to Step S101 is done.

When it is determined that all the temperatures Tk do not satisfy thecondition of Step S103, the process proceeds to Step S105. It is thendetermined whether or not all the temperatures Tk are not larger than aprescribed lower limit (Ts+δ3). In FIG. 4, it is shown using a symbol Vthat all the temperatures Tk satisfy a condition represented to theright of a colon, namely a condition of being not larger than the lowerlimit (Ts+δ3). Here, δ3 is smaller than δ1, and for example, δ3 is apositive value and 0.5° C. is adopted.

When all the temperatures Tk satisfy the condition of Step S104, it isdetermined that the cell temperatures of all the cells 2 haveexcessively cooled with respect to the target value. Therefore, theprocess proceeds to Step S106, to stop the cooling section 7. Theprocess then returns to Step

When at least one of the temperatures Tk does not satisfy the conditionof Step S104, proceeding to Step S107 is done. Then, the individualmeasured temperatures Tk are compared with a prescribed lower limit(Ts−δ2). Here, for example, δ2 is a positive value and 0.1° C. isadopted.

When one measured temperature Tk is not larger than the lower limit(Ts−δ2), it is determined that the cell 2 adjacent to the heat block 3where the sensor 4 k are arranged has been excessively cooled.Therefore, the heater 1 k responsive to the sensor 4 k is turned on.Then returning to Step S101 is done.

When any of the measured temperatures T1 to Tn is higher than the lowerlimit (Ts−δ2), proceeding to Step S109 is done. The individual measuredtemperatures Tk are compared with a prescribed upper limit (Ts+δ4).Here, 84 is larger than −δ2, and for example, δ4 is a positive value and0.1° C. is adopted.

When one measured temperature Tk is not smaller than the upper limit(Ts+δ4), it is determined that the cell 2 adjacent to the heat block 3where the sensor 4 k is arranged has been excessively heated. Therefore,the heater 1 k responsive to the sensor 4 k is turned off. Thenreturning to Step S101 is done.

When any of the measured temperatures T1 to Tn is lower than the upperlimit (Ts+δ4), proceeding to Step S900 is done. Then returning to StepS101 is done unless the operational switch is turned off. In FIG.4, StepS100 includes Steps S101 to S109 and return channels from Steps S104,S106, S108 and S110 to Step S101. Therefore, it can be understood thatStep S100 is repeated until the determination in Step S900 becomesaffirmative.

As thus described, the cooling section 7 is driven (S104) when thetemperature Tk not lower than the upper limit (Ts+δ1) is present and theheater 1 k is turned on (S108) when one measured temperature Tk is nothigher than the lower limit (Ts−δ2), whereby allowing enhancement inaccuracy of the temperature distribution as well as accuracy of thetemperature itself. In particular, since the cooling section 7 cools allthe cells 2 concurrently, an atmospheric temperature is equivalentlydecreased in on-off control of the heater even in the case of performingthe temperature control at a temperature lower than the atmospherictemperature, which is preferred.

Further, the cooling section 7 is not driven (S106) when all themeasured temperatures Tk are not larger than the lower limit (Ts+δ3),and the heater 1 k is turned off (S110) when one measured temperature Tkis not smaller than the upper limit (Ts+δ4), thereby allowingsuppression of excessive cooling or excessive heating of the cell 2.

As thus described, since the use of the temperature control techniqueaccording to the present invention allows accurate temperature controlof culture sensitive to a temperature, it is possible to uniformly set atemperature condition for a plurality of cultures.

Second Embodiment

FIG. 5 is a flowchart exemplifying the temperature controlling methodaccording to the present invention. In the present embodiment, StepsS800 and S200 are executed in this order after execution of Step S100 ofFIG. 4 until execution of Step S900.

Namely, when at least one temperature Tk is higher than the lower limit(Ts+δ3), all the temperatures T1 to Tn are lower than the upper limit(Ts+δ1), and any of the temperatures T1 to Tn is higher than the lowerlimit (Ts−δ2) and lower than the upper limit (Ts+δ4), the processproceeds to Step S800.

In Step S800, the target value Ts is calibrated to update to a newtarget value Tc according to the atmospheric temperature Ta of thetemperature controller. Further, the process proceeds to Step S200.

Step S200 is a step where the target value Ts in Step S100 is changed toa target value Tc. With the atmospheric temperature taken intoconsideration in the temperature control, an effect on the celltemperature exerted by the atmospheric temperature Ta can be made small.Since the temperatures T1 to Tn have already been measured in Step S100,the process corresponding to Step S101 in Step S100 may be omitted inStep 200.

Third Embodiment

In above-mentioned Steps S103 and S105, since n temperatures arecompared with the upper limit and the lower limit, the total of 2n ofcomparison operations are performed. However, once the maximum value Mof the temperatures T1 to Tn is obtained, it is possible to perform onlytwo comparison operations to obtain the effect shown in the firstembodiment.

FIG. 6 is a flowchart corresponding to FIG. 4, in which Step S100 hasbeen replaced by Step S300. Step S300 has a configuration where StepsS103 and S103 in Step S100 are respectively replaced by Steps S113 andS115, and a step S102 is added to between Step S101 and Step S113.

In Step S102, the maximum value M of the temperatures T1 to Tn iscalculated. In FIG. 6, a symbol max represents the maximum value of aplurality of values in parentheses to the right of the symbol max.

In step S113, it is determined whether or not the maximum value M is notsmaller than the prescribed upper limit (Ts+δ1). When this determinationis affirmative, at least one heated cell 2 is present, and thus theprocess proceeds to Step S104.

When the maximum value M is smaller than the prescribed upper limit(Ts+δ1), all the temperatures T1 to Tn are smaller than the prescribedupper limit (Ts+δ1), so proceeding to Step S115 is done.

In step S115, it is determined whether or not the maximum value M is notlarger than the prescribed lower limit (Ts+δ3). When this determinationis affirmative, the cell temperatures of all the cells 2 haveexcessively cooled with respect to the target value, and the processthus proceeds to Step S106.

When the maximum value M is larger than the lower limit (Ts+δ3),proceeding to Step S107, or further to Step S109 is done, and each ofthe measured temperatures Tk is respectively compared with theprescribed lower limit (Ts−δ2) and upper limit (Ts+δ4).

FIG. 7 is a flowchart corresponding to FIG. 5, in which Steps S100 andS200 are replaced by Steps S300 and S400, respectively, and it ispossible to obtain the effect shown in the second embodiment.

Step S400 is a step where the target value Ts is changed to a targetvalue Tc with respect to Step S300. Since the temperatures T1 to Tn havealready been measured in Step S300, the process corresponding to StepsS101 and S102 in Step S300 may be omitted in Step S400.

Naturally, Step S800 and Step S400 may be executed after execution ofStep S100. In such a case, it is necessary to obtain the maximum value Min Step S400. Further, Step S800 and Step S200 may be executed afterexecution of Step S300.

Fourth Embodiment

FIG. 8 is a block diagram, exemplifying a technique for correctingcontrol by the heater group 1 and the cooling section 7 by means of theatmospheric temperature Ta, where operations of the first to thirdembodiments are accomplished. The temperature controller furtherincludes a thermometer 40, a storage section 5, and a control section 6.The control section 6 controls the heater group 1 and the coolingsection 7 according to the flowcharts shown in FIGS. 4 to 7. Thethermometer 40 measures the atmospheric temperature Ta of circumstancesunder which the temperature controller has been set, and the storagesection 5 storages calibration data.

The calibration data is obtained, for example, in the following manner.A cell temperature controlled by using Step S100 is previously set ateach of different atmospheric temperatures Ta. The relation between thetarget value Ts of the heater temperature and the cell temperature ateach of the atmospheric temperatures Ta is represented by a table, whichis then adopted as calibration data.

The control section is provided with not only the target value Ts of thecell temperature but also with the atmospheric temperature Ta from thethermometer 40 and the calibration data from the storage section 5.According to the atmospheric temperature Ta, the control section 6obtains a new target value Tc on the basis of the target value Ts of thecell temperature and the calibration data such that the cell temperatureis the target value Ts. The control section 6 then executes Step S200 byusing the target value Tc after update.

FIG. 9 is a block diagram exemplifying another technique for correctingthe control by the heater group 1 and the cooling section 7 by means ofthe atmospheric temperature Ta. The temperature controller includes acalculating section 8 in place of the storage section 5.

The calculating section 8 is provided with a prescribed function, theatmospheric temperature Ta and the target value Ts. The target value Tsis, for example, provided from the control section 6.

The function is, for example, obtained as follows. A cell temperaturecontrolled by using Step S100 or Step S300 is previously measured ateach of different atmospheric temperatures Ta. The relation among theatmospheric temperature Ta, the target value Ts and the cell temperatureis adopted as the function.

By using the function, the calculating section 8 obtains a new targetvalue Tc from the atmospheric temperature Ta and the target value Tssuch that the cell temperature is the target value Ts. By using thetarget value Tc after update, the control section 6 executes Step S200or Step S400.

The foregoing temperature controller can be utilized not only in thecase of culturing microorganisms or the like but also in the case ofmeasuring an amount, effect, etc. of a chemical material by usingmicroorganisms or the like as mediums, for example through the use ofrespiration activity of microorganisms or the like, or in a case wheremicroorganisms or the like come into extinction.

The present invention was specifically described, but the abovedescriptions are exemplifications in all aspects and the presentinvention is not limited thereto. It is understood that innumerablemodified examples which are not exemplified can be conceived withoutdeviating from the range of the present invention.

1. A temperature controlling method, to control a temperature controllercomprising: a temperature-controlled object whose temperature is to becontrolled; heaters for heating a plurality of places of saidtemperature-controlled object; and a cooling section or cooling thewhole of said temperature-controlled object, the method executing: (a) astep of measuring temperatures of said plurality of places; (b) a stepof driving said cooling section when at least one of said temperaturesof said places is not lower than a first upper limit; and (c) a step ofdriving said heater for heating one of said places when said temperatureof the one of said places is not higher than a first lower limit.
 2. Thetemperature controlling method according to claim 1, further executing:(d) a step of not driving said cooling section when all of saidtemperatures of said places are not higher than a second lower limit;and (e) a step of not driving said heater for heating one of said placeswhen said temperature of the one of said places is not lower than asecond upper limit.
 3. The temperature controlling method according toclaim 2, wherein said second lower limit is lower than said first upperlimit, and is a value obtained by adding a third positive value to atarget value of a temperature of said temperature-controlled object, andsaid second upper limit is higher than said first lower limit, and is avalue obtained by adding a fourth positive value to said target value.4. The temperature controlling method according to claim 3, furtherexecuting: (f) a step of calibrating to update said target value to anew target value according to an atmospheric temperature of saidtemperature controller when at least one of said temperatures of saidplaces is higher than said second lower limit, all of said temperaturesof said places are lower than said first upper limit, and any of saidtemperatures of said places is higher than said first lower limit andlower than said second upper limit, and again executing said steps (b)and (c) by using said target value updated in said step (f).
 5. Thetemperature controlling method according to claim 4, again executingsaid steps (d) and (e) by using said target value updated in said step(f).
 6. The temperature controlling method according to claim 1, whereinsaid temperature-controlled object has a plurality of containers capableof housing cultures.
 7. The temperature controlling method according toclaim 1, wherein said first higher limit is a value obtained by adding afirst positive value to a target value of a temperature of saidtemperature-controlled object, and said first lower limit is a valueobtained by subtracting a second positive value from said target value.8. The temperature controlling method according to claim 6, wherein saidfirst higher limit is a value obtained by adding a first positive valueto a target value of a temperature of said temperature-controlledobject, and said first lower limit is a value obtained by subtracting asecond positive value from said target value.
 9. A temperaturecontroller, comprising: a housing section for housing a plurality ofcontainers whose temperatures are to be controlled; a cooling sectionfor concurrently cooling all of said plurality containers housed in saidhousing section; a plurality of heaters for selectively heating saidplurality of containers; and a plurality of sensors for measuringtemperatures of respective places heated by said plurality of heaters.10. The temperature controller according to claim 9, further comprisinga control section for controlling the drive of said cooling section onthe basis of a target value of temperatures of said containers andresults of temperature measurement by said plurality of sensors, andcontrolling the drive of said heaters responsive to said plurality ofsensors on the basis of each said results of temperature measurement bysaid sensors.
 11. The temperature controller according to claim 10,further comprising: a sensor for measuring an atmospheric temperature;and a calculating section for updating said target value on the basis ofsaid atmospheric temperature and said target value.
 12. The temperaturecontroller according to claim 10, further comprising: a sensor formeasuring an atmospheric temperature; and a storage section for storingcalibration data that provides a calibration value on the basis of saidatmospheric temperature and said target value, wherein said controlsection updates said target value with said calibration value on thebasis of said calibration data, said atmospheric temperature and saidtarget value.